No, I never said anything like 'Unhelmeted cyclists are invincible'. I specifically said that luck plays a large part in sustaining head injuries. In your case, in all likelihood, your helmet made no difference whatsoever and you would have been injured with or without it. And we know this because even helmet manufacturers state that their bicycle helmets are not designed to prevent the sort of injury you received.

As an aside, for the folks here who are suffering from confirmation bias, your story is precisely an example of that phenomenon. You want to believe that it was your foresight and intelligence in wearing a helmet that day which saved your life. I get that -- everyone wants to believe that they are in control, and no one wants to believe that they just got lucky. So everyone wants to believe that, as long as they wear their dainty little plastic hat, they will be safe. And I get that too, feeling safe is nice. But feeling safe is not being safe, and it is important to recognize the difference.

To the point, an equally-valid interpretation of your story is that your helmet did a very poor job of protecting your brain, and you wound up in a coma despite wearing your hat.